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76 lines
2.0 KiB
C++
76 lines
2.0 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef WebAudioUtils_h_
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#define WebAudioUtils_h_
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#include <cmath>
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#include "AudioParamTimeline.h"
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namespace mozilla {
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class AudioNodeStream;
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namespace dom {
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struct WebAudioUtils {
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static bool FuzzyEqual(float v1, float v2)
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{
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using namespace std;
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return fabsf(v1 - v2) < 1e-7f;
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}
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static bool FuzzyEqual(double v1, double v2)
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{
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using namespace std;
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return fabs(v1 - v2) < 1e-7;
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}
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/**
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* Computes an exponential smoothing rate for a time based variable
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* over aDuration seconds.
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*/
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static double ComputeSmoothingRate(double aDuration, double aSampleRate)
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{
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return 1.0 - std::exp(-1.0 / (aDuration * aSampleRate));
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}
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/**
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* Converts AudioParamTimeline floating point time values to tick values
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* with respect to a source and a destination AudioNodeStream.
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*
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* This needs to be called for each AudioParamTimeline that gets sent to an
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* AudioNodeEngine on the engine side where the AudioParamTimeline is
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* received. This means that such engines need to be aware of their source
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* and destination streams as well.
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*/
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static void ConvertAudioParamToTicks(AudioParamTimeline& aParam,
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AudioNodeStream* aSource,
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AudioNodeStream* aDest);
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/**
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* Converts a linear value to decibels. Returns aMinDecibels if the linear
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* value is 0.
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*/
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static float ConvertLinearToDecibels(float aLinearValue, float aMinDecibels)
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{
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return aLinearValue ? 20.0f * std::log10(aLinearValue) : aMinDecibels;
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}
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/**
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* Converts a decibel to a linear value.
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*/
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static float ConvertDecibelToLinear(float aDecibel)
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{
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return std::pow(10.0f, 0.05f * aDecibel);
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}
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};
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}
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}
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#endif
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